[squeak-dev] Re: Resume Problems

Zulq Alam me at zulq.net
Fri Dec 19 11:55:37 UTC 2008

Hi Stéphane,

Stéphane Rollandin wrote:
> hello,
>> SoupTag>>doesNotUnderstand: aMessage
>>     (aMessage arguments size = 0)
>>         ifFalse: [^ super doesNotUnderstand: aMessage].
>>     ^ attributes
>>         at: aMessage selector
>>         ifAbsent: [super doesNotUnderstand: aMessage]
> this can be simpler, since the dictionary lookup will not confuse #id 
> with #id:, so you can get rid of the arguments size test:

Agreed, thanks.

> if there is only one element to be found, the order in which you search 
> for it does not matter. 

There could be many and order matters. This method is really findFirst, 
but I'm trying to keep the names analogous to the library I'm porting.

> now I must say your overall design seems to me very complex and really 
> overusing the DNU mechanism. it should be possible to do what you want 
> in a much simpler way, but since I don't know what you want to implement 
> exactly I will not elaborate on this.

The goal is to be able to concisely specify complex find: queries 
without having to worry about whether a tag has an attribute. This 
shouldn't mean that a tag swallows messages all the time.

A tag may represent a structure like:

<p class="outer">
   <p id="1">ID 1</p>
   <p class="A">CLASS A
     <p blah="blah" id="1">BLAH 1</p>
     <p blah="blah" class="A">BLAH 2</p>

Where each p is a tag, and nested p's are children. To find the BLAH 2:

   blah2 = tag find: [:each | each blah = 'blah' and: [each class = 'A']]

Each tag in the hierarchy before the desired element will throw an MNU 
when an attribute is missing. This is desired, i.e.:

   blah2 blah " blah"
   (blah2 attributeAt: 'class') " A "
   blah2 id " should signal an MNU "

Now, maybe catching the MNU is not the right way to do this but I'm not 
sure how else to do it while leaving the syntax so concise.


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